1. Field of the Invention
This invention relates to a connector connectable and disconnectable without requiring force, which is small-sized and easy in operation.
2. Description of the Prior Art
In electronic devices using a number of printed circuit boards, such as computers, parts of the printed circuit boards have been used as male contacts adapted to be inserted into multiple connectors to connect them with other circuits. In this case, however, the multiple connectors in general require great forces in inserting and removing the printed circuit boards. Particularly, when many printed circuit boards are arranged side by side with small intervals, they make it difficult to apply force and hence insertion and removal of the circuit boards are difficult.
In order to avoid such difficulties, the inventors of this application had proposed a connector connectable and disconnectable with little force, so called "ZIF connector" as shown in FIGS. 1a and 1b connected to a printed circuit board and in FIGS. 2a and 2b disconnected from the printed circuit board.
With this connector, a lever having a lower end engaging with one end of an insulating casing 1 at 1a is pivotally connected at a mid portion to an extension 2a of a slide plate 2 at 3a. When an upper end of the lever is moved or swung to the right from a position in FIG. 1a to that in FIG. 2a, the slide plate 2 is moved to the right so as to cause OFF-projections 2b provided at a lower end of the slide plate to ride over lifting protrusions 1b of the insulating casing 1, so that the slide plate 2 is raised with the aid of a camming action of the OFF-projections and the lifting protrusions as cam means. On the other hand, an ON-OFF plate 4 is supported by the slide plate 2, with a T-shaped support projection 4a of the ON-OFF plate 4 slidably fitted in an inverted T-shaped support groove 2c formed in an upper end of the slide plate over its full length. When the slide plate 2 is raised in the above manner, the ON-OFF plate 4 located on the slide plate 2 is simultaneously raised while being guided by a right-hand wall surface 1c preventing the ON-OFF plate 4 from moving together with the horizontal movement of the slide plate 2, to insert the ON-OFF plate 4 between a pair of contacts 5 as shown in FIG. 2b.
When the lever 3 is returned to the left viewed in FIG. 1a, the slide plate 2 is returned to its original position and the ON-OFF plate 4 is lowered guided by a left-hand wall surface 1d of the insulating casing 1 together with the slide plate 2 lowering downward and moving to the left, thereby removing the ON-OFF plate 4 from the pair of the contacts 5.
With this arrangement, after the ON-OFF plate 4 has assumed between the contacts 5 to keep the female contacts to be opened as shown in FIG. 2b, a printed circuit board 6 is inserted into a V-shaped recess or groove 4b of the ON-OFF plate 4 through an insert aperture 1e and then the ON-OFF plate is removed from the pair of contacts 5 to bring the female contacts into contact with the printed circuit board 6, thereby completing the connection of the connector without requiring any force for inserting the printed circuit board 6 as shown in FIG. 1b. In order to remove the printed circuit board already inserted, the ON-OFF plate is inserted between the pair of contacts 5 to enable the printed circuit board 6 to be removed without requiring any force in the same manner as the above.
Moreover, the raising and lowering of the ON-OFF plate 4 caused by the slide plate 2 is effected by the operation of the lever 3. As a length l.sub.2 from the pivot point 3a to the top of the lever 3 is made much longer than a length l.sub.1 from the pivot point 3a to the lower end of the lever, the lever can be operated only with a small force even if contact pressures resulting from the resilience of the pair of contacts 5 are high enough. Furthermore, the slide plate 2 and the ON-OFF plate 4 undergo only linear vertical and horizontal movements which are very simple movements sufficient to avoid any trouble. In a prior art, for example, a connector connectable and disconnectable without force as shown in FIGS. 3a, 3b and 3c, a flat cam plate 8 is rotated by rotating a handle 7 provided at one end of the cam plate to open pairs of contacts 5 away from each other. The flat cam plate is torsionally deformed so that the end of the flat cam plate remote from the handle 7 rotates only an angular displacement smaller than that of the handle 7, with the result that the pairs of contacts remote from the handle open only insufficient amounts, and the cam plate 8 is often fractured upon being subjected to an excess force. Such troubles are not the case in this connector which the inventors had proposed.
On the other hand, however, with the connector having the lever 3 for operating the slide plate 2 as shown in FIGS. 1 and 2, the lever 3 is unavoidably made long in order to operate it with a small force, in the event of a large number of contacts of the connectors or multiple connectors.
There is often a case that a number of printed circuit boards 6 are arranged one upon the other spaced only with small clearance in order to provide a small-sized connector as shown in FIG. 4. In this case, even if an elongated lever is not needed in consideration of the operating force, ends of short levers 3 are located between the printed circuit boards 6a and 6b, so that they are difficult to operate. It is therefore in this case needed to elongate the levers out of the printed circuit boards 6a and 6b as shown in broken lines in FIG. 4. As the result, the connectors having elongated levers extending beyond edges of the printed circuit boards are bulky and require larger packaging boxes for packaging. In packaging these connectors in boxes or incorporating them in electronic devices, moreover, these levers are likely to be subjected to excess forces resulting in fractures of the levers.